The invention relates to a check valve, in particular for use in an implantable artificial bladder, which prevents on the one hand a return flow and has on the other hand a predetermined opening pressure.
There are cases in which check valves are implanted as implants into human bodies. In "The Journal of Urology", Vol. 151, 1996, 2094-2097, an artificial bladder is described which comprises two implant containers which are capable of restoring their original form and which are connected on the one hand through a catheter with the kidneys and on the other hand through a Y-piece with the urethra. The containers, which tend to expand, take up fluid from the kidneys. To discharge the fluid, the patient presses onto the containers so that the fluid flows into the urethra. Each container comprises check valves both at its inlet and its outlet, which prevent on the one hand reflux to the kidney and on the other hand intake of air during the filling phase. These check valves are foil valves which are also referred to as "duckbill valves". Such foil valves have a very low opening pressure so that there is the danger of un-intentional emptying of the containers and thus the danger of incontinence. Furthermore, incrustrations tend to deposit on the implanted foil valves so that these tend to leak.
Artificial bladders with the corresponding valves are also described in EP 0 282 157 B1 and EP 0 393 714 A2. Here relatively complex check valves are provided which involve the danger of failure after they have been implanted for a long time. U.S. Pat. No. 4,497,074 describes a prosthetic bladder. The ureteral catheters leading into the bladder are provided with foil valves.
Furthermore, U.S. Pat. No. 4,722,731 describes a valve comprising a valve member in the form of a flexible hose into which extends an inlet duct from the one end and an outlet duct from the other end. The flexible hose is biased in such a way that it blocks the connection between the inlet duct and the outlet duct. If the opening pressure exceeds a predetermined value, the valve opens. Such a pressure relief valve, too, is of complex design and comprises narrow ducts through which fluid must flow.